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atari trackball as a TI-99 joystick, not perfect


hloberg
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I have just made an interface for the Atari trackball to the TI-99/4a. The Atari trackball works like a joystick that needs a +5 to power the sensors. it's essentially an upside down ball mouse. So what I did was create a standard Atari to Ti-99 joystick interface cable then on PIN 7 I attached a +5 from a battery for the Atari trackball sensors. believe it or not it works.

Except, and this is the odd part I can't figure out, when the trackball is attached the keyboard display automatically goes into lower case. clicking the alpha lock does nothing and pressing shift will make the upper case letters appear but it will default back to lower case. also, you still have to turn off the alpha lock to enable 'up' on the trackball. this effect happens rather the +5 is attached or not.

doesn't seem to effect the TI-99 adversely except throwing it into lower case.

ideas?

 

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You might want to put a diode network in there to fully isolate the signals and see if that eliminates the issues. . .similar to what Wico did with their joystick adapter. Most adapters just put in the correct cross-wiring, but Wico put isolation diodes in too, which was one of the reasons their adapter was pretty much the gold standard BITD.

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No ideas... but I'm requesting photos! :grin:

This is a neat idea because that trackball, IF I'M NOT MISTAKEN, is cheaper and easier to come by than the

<< TI version of the Wico >>.

BTW - A trackball is great with Stuart's Internet browser.

 

Is the photo below like the one you are working with?

trackball.jpg

 

Next Thursday I will have a write up on the trackball, on my project website, starting with the disassembly and clean up of the trackball. I will have lots of pictures. And yes, that is it.

https://fieldmouseprojects.wordpress.com/

Edited by hloberg
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You might want to put a diode network in there to fully isolate the signals and see if that eliminates the issues. . .similar to what Wico did with their joystick adapter. Most adapters just put in the correct cross-wiring, but Wico put isolation diodes in too, which was one of the reasons their adapter was pretty much the gold standard BITD.

Any idea what diodes were used on the Wico i.e. value wise?

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I think I fixed the issue. I put a diode on the 'UP' line and now everything works as it should. I want to run more test but so far, so good.

I will have pictures and a full write up in a couple weeks on my project website. I'm about to get real busy or I would have it up sooner.

I still contemplating putting diodes on all the lines but the Atari joystick adapter I created previously worked fine without them so I might not; just on the 'UP' line.

Also found that using 3 AA batteries work fine. I tried using a +5 power brick but it caused all kinds of problems, More likely the +5 wasn't pure enough.

Here is what the test setup look like.

post-28093-0-54914000-1467057250_thumb.jpg

like I said, I do a full write up and pictures later.

thanks all for the help.

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ran more test. The 1N914 diode on the UP line works fine.

the trackball controller works well with games Buck Rogers and Centipede. OK with games like demon attack and no so good with games like munchman.

of course, that could be said of any trackball.

I actually played a better game of Buck Rogers than I played with the joystick.

 

Attached is my cryptic notes. Ignore the colors, I used an old serial cable and cut it in half for the cable.

The +5 is a three AAA battery holder.

As I said, I'll have more pics and details later.

 

You can get one of these trackballs for about $15.00 or less. Diode $0.25, old serial cable $3.00. Then supply a +5 in what ever way you see fit. Optionally put in case.

 

IMG_20160628_0001.pdf

Edited by hloberg
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  • 2 weeks later...

Here it is. Complete write up, pictures and links.

https://fieldmouseprojects.wordpress.com/2016/07/07/part-2making-an-interface-for-atari-trackball-to-ti-994a/

I hope this makes sense.

Most important is powering +5 to pin 7 on Atari side, -5 to common ground, 1N914 diode on the UP line.

then follow the instructions on mainbyte for creating an Atari to TI-99 interface.

Note: I initially had a power supply instead of batteries but got some weird problems. Those problems might go away if a diode is put on all the lines but I never tested it. AAA batteries might also work but I had a AA battery holder laying around. Any voltage from 4.5 to 6 seems OK.

Also, read the previous post because these trackballs really get all corroded inside after a while and the ball motion gets very jerky.

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Nice blog entry! :thumbsup: :thumbsup: :thumbsup: :thumbsup: :thumbsup:

Might I make a suggestion? If you've not tried already, try playing Neverlander by Marc Hull with your trackball. It's an excellent game and plays wonderfully with a trackball.

 

20160701_180027.jpg?w=361&h=481&crop=1

 

Also, if you could, it would be nice to get an update in the future on how long the batteries last.

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Nice blog entry! :thumbsup: :thumbsup: :thumbsup: :thumbsup: :thumbsup:

Might I make a suggestion? If you've not tried already, try playing Neverlander by Marc Hull with your trackball. It's an excellent game and plays wonderfully with a trackball.

 

20160701_180027.jpg?w=361&h=481&crop=1

 

Also, if you could, it would be nice to get an update in the future on how long the batteries last.

Will try Neverlander, thanks. Buck Rogers work really well. As for battery life, the draw on the batteries looks fairly small. But I put the battery pack on top so that I could remove the batteries when stored. I'll try to keep using the same batteries to get a good feel of the battery life. As I posted, if you are willing to tie all the lines with diodes or use a real good +5 power source you could power it with a plug. You could also use rechargeable batteries if you wanted to get fancy.

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Cool! I bought one of those Atari trackballs years ago for my TI but never got it hooked up correctly to work. I didn't realize all it might take is outboard power+diode to get it going. Disassembled and parts scattered years ago. I think I saved the cue ball if I everr found a pool table cheap that needed one. :lol:

 

Power needs can't be too great, since it was normally provided by the Atari joystick port. How many hours straight would you play Buck Rogers anyway? ;) Wire one up and find out. If it's an issue, switch to D-cells.

 

For that matter, if cheap battery power is an issue, buy a Harbor Freight 18v drill battery and remove the sub-C cells. You get 15 of them from one pack, good for lots of experimenting and cost under a buck apiece in 1200mA and about a buck-twenty in 1500mA size. Four of 'em would provide about 4.8v, perfect! Don't even need a holder, as they're solder-tabbed.

-Ed

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For that matter, if cheap battery power is an issue, buy a Harbor Freight 18v drill battery and remove the sub-C cells. You get 15 of them from one pack, good for lots of experimenting and cost under a buck apiece in 1200mA and about a buck-twenty in 1500mA size. Four of 'em would provide about 4.8v, perfect! Don't even need a holder, as they're solder-tabbed.

-Ed

Good 'cheap' idea. I like cheap. :-D So far, the power requirements haven't been great. Tonight I plan to play a lot of games with it Since I finished my FlashROM 99 and itching to try both out.

One thing I did mention is I think a plug in +5 source would work IF you had diodes on all line to be sure the voltage was always going in one direction.

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Ramp up that power!

Been playing with it today and don't see too much of a drop off of power from the standard Duracells.

Play-ability is a mixed bag though.

Since it's a trackball being seen as a joystick you are still tied to joystick speeds across the screen. flick the ball fast and the gunner still only moves as fast as a holding down the joystick.

But accuracy is different. I feel I can more accurately control where I want the gunner to be.

Therefore, Centipede, where you got to flash across the screen a lot, not much better. Buck Rogers where you are trying to fit between the poles, easier.

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Okay, I tired Buck Rogers and it does work pretty well. Thanks for the heads up on that.

Now this begs the question, "What are the top 10 programs for trackball use?"

...

I know you guys, you've got some answers!

 

I see nothing logically wrong with “Okay, I tired Buck Rogers and it does work pretty well.” You probably meant “tried”; but, that does not turn it into a logical fallacy.

 

...lee

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I like Demon Attack with the trackball, as the TI version of Demon Attack goes. I have never been a fan of how they changed Demon Attack for the TI from the Atari.

As for Centipede ,It didn't move across the screen fast but then the joystick version doesn't doesn't move fast enough either for me.

Be interesting to see how well it does with a drawing program.

still playing with it.

Edited by hloberg
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